DE102016002128B4 - A light beam absorbing optical absorber - Google Patents

Abstract

An optical absorber (10) comprising: a first light absorbing body (11) configured to receive incident light via an input port (10a) and to partially absorb and partially reflect the incident light; anda second light absorbing body (12) arranged to partially absorb the incident light reflected by the first light absorbing body (11) and to partially reflect the incident light to the first light absorbing body (12), the first light absorbing body and the first light absorbing body second light-absorbing bodies form rectangular parallelepipeds defined by planes, the end portions of the first light-absorbing body and the second light-absorbing body being connected to each other downstream of the direction in which the laser light propagates; and wherein a light absorption of the second light-absorbing body (12) is set higher than a light absorption of the first light-absorbing body (11).

Description

Field of the invention

The invention relates to an optical absorber which absorbs a light beam.

To the state of the art

During maintenance work on an optical resonator or an excitation energy source in an industrial laser oscillator, the laser radiation is preferably set in oscillation and emitted without laser radiation being led out of the laser oscillator. For safety in such maintenance work, the laser oscillator has a device which completely absorbs and absorbs laser radiation.

Such a device, i. An optical absorber uses a light-absorbing body with low reflectivity for laser light and high absorbance for absorbing laser light. A special optical absorber is made, for example, by a surface treatment or a high laser light absorption coating on a material having high thermal conductivity, such as copper or aluminum. Another optical absorber is designed to receive the laser light several times and gradually attenuate it.

The JP 2005-140 964 A describes, by way of example, an optical absorber with a reflecting component which disperses the laser light before it enters a light-absorbing body. The JP 2003-080 390 A describes an optical absorber with partial light emission from an exit aperture, wherein light is incident through an entrance aperture and the exiting laser light is incident into a light absorbing body disposed in the radiation path behind the exit aperture to absorb the light. The JP H05-050 757 U and the JP 2012-204 374 A describe optical absorbers in which the reflectivity at one end of an absorbent body is improved.

BRIEF DESCRIPTION OF THE INVENTION

In the JP 2005-140 964 A however, a reflective body is required for scattering laser light, while according to the JP 2003-080 390 A is required to form a light-absorbing body and also an outlet opening in the optical absorber. In the JP H05-050 757 U and the JP 2012-204 374 A it is necessary to increase the reflectivity with a surface treatment.

As a result, an additional component or an additional surface treatment is required in the prior art. This increases the number of components and processes, which in turn increases manufacturing costs and also causes problems in terms of quality and functional reliability or the optical absorber is also large and expensive.

The present invention is associated with these problems and aims to provide a highly reliable and small optical absorber which is inexpensive to produce and requires no additional component or surface treatment.

According to the invention, an apparatus according to independent claim 1 is provided. Developments are set forth in the dependent claims.

According to the invention, an optical absorber of a first example is provided with a first light-absorbing body and a second light-absorbing body. The first light-absorbing body receives incident light from an input port and partially absorbs and reflects the incident light. The second light-absorbing body partially absorbs incident light reflected by the first light-absorbing body, and partially reflects the incident light toward the first light-absorbing body. The light absorption of the second light-absorbing body is set higher than the light absorption of the first light-absorbing body.

According to a second example, in the first example, preferably, a space surrounded by the first light-absorbing body and the second light-absorbing body except for the entrance opening is closed.

According to a third example, in the first or second example, preferably, the incident light and the light reflected by the second light-absorbing body overlap each other at least partially in the first light-absorbing body.

According to a fourth example, in the first to third examples, preferably, the optical absorber has a cooling unit that cools the first light-absorbing body and / or the second light-absorbing body.

According to a fifth example, in the fourth example, preferably, the optical absorber further has a connecting member which includes the first light-absorbing body and the second light-absorbing body for heat transfer with each other.

According to a sixth example, in the first to fifth examples, preferably, the first light-absorbing body has a reflectance of between 40% and 60%.

According to a seventh example, in the first to sixth examples, preferably, the second light-absorbing body has a reflectance greater than 0% but less than or equal to 10%.

These and other objects, features and advantages of the invention will become more apparent from the following description of typical embodiments, which are illustrated in the figures.

list of figures

• 1 Fig. 10 is a side view showing an optical absorber according to a first embodiment of the invention;
• 2 Fig. 11 is a side view of an optical absorber according to a second embodiment of the invention;
• 3 Fig. 16 is a graph showing the relationship between light resistance and reflectivity and light absorptivity; and
• 4 Fig. 7 is a graph showing the relationship between the attenuation ratio and the number of reflections.

DESCRIPTION IN DETAIL

Embodiments of the invention will now be described with reference to the figures. Like reference numerals are used in the figures for like components. To promote understanding, the figures use different scales.

1 Fig. 10 is a side view for explaining an optical absorber (absorber) according to a first embodiment of the invention. The optical absorber 10 has a first light-absorbing body 11 and a second light-absorbing body 12 which according to 1 form an acute angle with each other. An annular component 10b with an entrance opening 10a is at the end portions of the first light-absorbing body 11 and the second light-absorbing body 12 arranged. The optical absorber 10 can also without the use of the annular component 10b from the first light-absorbing body 11 and the second light-absorbing body 12 be shaped.

The first light-absorbing body 11 and the second light-absorbing body 12 according to 1 each form a right-angled parallelepiped formed by planes, but with the first absorbent body 11 and the second light-absorbing body 12 partially also curved surfaces may have. Such an optical absorber 10 is used in maintenance work on an optical resonator or on an excitation energy source in a laser oscillator (not shown).

Incident light is transmitted through the entrance opening 10a according to 1 from the first light-absorbing body 11 receive. The first light-absorbing body 11 has a relatively high light resistance and thus a relatively high reflectivity for the laser light. In contrast, the second light-absorbing body has 12 a smaller light resistance than the first light-absorbing body 11 and therefore, a reflectivity for the laser light which is smaller than that of the first light-absorbing body 11 ,

3 Fig. 10 is a graph showing the relationship between the light resistance and the reflectivity and the light absorptivity. 3 shows the light resistance and the reflectance on the ordinate and the light absorbance on the abscissa. As 3 shows, with increasing light resistance or reflectance, the light absorption capacity becomes smaller. The smaller the light resistance and reflectivity, the greater the light absorbance. Therefore, the second light-absorbing body has 12 a light absorptivity greater than that of the first light-absorbing body 11 ,

As described above, the optical absorber 10 according to the invention, a first light-absorbing body 11 with a high light resistance against the laser light and a second light-absorbing body 12 having a high light absorbance for absorbing laser light. Accordingly, therefore, the optical absorber 10 according to the invention, two opposite properties: resistance to laser light and the property to effectively absorb laser light.

As 1 shows, light is entering the optical absorber 10 over the entrance opening 10a as incident light, first from a primary light receiving surface 11a of the first light-absorbing body 11 receive. Although the intensity of the incident light is relatively high, the light resistance and the reflectivity of the first light-absorbing body are 11 high. Therefore, even when the laser light is received as the incident light, the first light-absorbing body is generated 11 no heat due to absorption of laser light and thus suffers no damage or disturbances. A part of the received laser light is in the first light-absorbing body 11 absorbed. Remaining laser light, which is not in the first light-absorbing body 11 is absorbed, toward the second light-absorbing body 12 reflected as reflected light.

The reflected light is from a secondary light receiving surface 12a of the second light-absorbing body 12 according to 1 receive. The light resistance and the reflectivity of the second light-absorbing body 12 are, as stated above, low. From the second light-absorbing body 12 but received light is from the first light-absorbing body 11 reflected light which has a relatively low intensity. Therefore, the second light-absorbing body generates 12 Although it has a relatively low light resistance, no heat upon absorption of the laser light and therefore suffers no interference or disturbance.

Since the light absorptivity of the second light-absorbing body 12 is high, the second light-absorbing body absorbs 12 a large part of the reflected light and reflects this partially in the direction of the first light-absorbing body 11 , As 1 shows, this laser light reflection is alternately between the first light-absorbing body 11 and the second light-absorbing body 12 repeated, so that the laser light in the optical absorber 10 is absorbed.

Corresponding 1 are the end portions of the first light-absorbing body 11 and the second light-absorbing body 12 connected in the propagation direction of the laser light. This means that of the first light-absorbing body 11 and the second light-absorbing body 12 enclosed space is closed except the entrance opening 10a , With such an arrangement, no laser light comes out of the optical absorber 10 , whereby its safety properties are improved.

Since the end portions of the first light-absorbing body 11 and the second light-absorbing body 12 connected to each other, the number of reflections in the optical absorber 10 be increased so that laser light is absorbed reliably. By direct connection of the first light-absorbing body 11 and the second light-absorbing body 12 For example, it is possible to minimize the number of components of the device, and thus the optical absorber 10 be produced with little effort.

As described above, the first laser light first has receiving light-absorbing bodies 11 a light resistance and a reflectivity higher than the second light-absorbing body 12 , which receives light passing through the first light-absorbing body 11 is reflected. This makes it possible to reduce the risk of damage to the first light-absorbing body 11 by incident light of high intensity. Since the second light-absorbing body 12 through the first light-absorbing body 11 attenuated, reflected light can also at the second light-absorbing body 12 Disturbances are avoided. The second light-absorbing body 12 has a light absorptivity larger than the first light absorbing body 11 and therefore can efficiently absorb reflected light.

As described above, with the present invention, neither an additional component nor an additional surface treatment need be used because the optical absorber 10 is formed with only the first light-absorbing body 11 and the second light-absorbing body 12 with different reflectivities and light resistances. Thus, the invention enables a highly reliable optical absorber 10 which can be produced at low cost.

Had the second light-absorbing body 12 the same light resistance and the same reflectivity as the first light-absorbing body 11 , is the light absorption of the second light-absorbing body 12 low (cf. 3 ). Therefore, the number of reflections in the optical absorber 10 be increased, which is the size of the optical absorber 10 increased.

Had the first light-absorbing body 11 the same light resistance and the same reflectivity as the second light-absorbing body 12 , is the light resistance of the first light-absorbing body 11 low, although its light absorption is high. In other words, the light resistance of the entire optical absorber 10 is low. Therefore, the angle of incidence of the first light-absorbing body must be 11 incident light is increased to the intensity of the laser light per unit area in the first light-absorbing body 11 to reduce. This results in a large optical absorber 10 ,

In contrast, in the present invention, the first light-absorbing body 11 and the second light-absorbing body 12 different reflectivities and light resistances and an increase in the size of the optical absorber 10 can be avoided.

It is generally difficult to have a stable second light-absorbing body 12 with low light resistance and low reflectivity, and the use of a second light absorbing body 12 with low light resistance and low reflectivity results in higher production costs for the optical absorber 10 , According to the present invention, the second light-absorbing body forms 12 only a part of the optical absorber 10 and therefore the optical absorber 10 can be produced according to the invention at low cost.

The larger the angle Θ, the first light-absorbing body 11 and the second light-absorbing body 12 include, the smaller the size of the optical absorber 10 , But since in such a case, the incident surface of the first light-absorbing body 11 incident light is small, is the intensity of the laser radiation per unit area in the first light-absorbing body 11 high.

The primary light receiving surface 11a of the first light-absorbing body 11 is preferably coated with black nickel. This partially increases the light resistance and the reflectance for the laser light. The entire surface of the first light-absorbing body 11 which the second light-absorbing body 12 may be coated with black nickel. Then the size of the optical absorber 10 be reduced by setting a relatively large angle Θ.

Are the light resistance and the reflectivity of the first light-absorbing body 11 small, the angle Θ should be small, the intensity of the laser light per unit area at the first light-absorbing body 11 to reduce. In this case, the optical absorber 10 a relatively large total length L (see 1 ). Therefore, the total length L of the optical absorber 10 keeping small is the first light-absorbing body 11 preferably coated with black nickel to increase its light resistance and reflectivity.

In particular, the secondary light-receiving surface becomes 12a of the second light-absorbing body 12 preferably subjected to a blackening chromium treatment. This makes it possible to increase the light absorptivity by partially lowering the light resistance and the reflectance for the laser light. A blackening chromium treatment may take place with respect to the entire surface of the second light-absorbing body 12 which is the first light-absorbing body 11 opposite. Then, the laser light can be absorbed while reducing the number of reflections in the optical absorber 10 ,

2 is a side view illustrating an optical absorber according to a second embodiment of the invention. Follow according to 2 Laser light over the entrance opening 10a as incident light in the optical absorber 10 It first enters through a primary light-receiving surface 11a of the first light-absorbing body 11 receive. A part of the received laser light becomes in the first light-absorbing body 11 absorbed. A remaining part of the laser light, which in the first light-absorbing body 11 is not absorbed, is towards a second light-absorbing body 12 reflected as reflected light.

Then, the reflected light is transmitted through a secondary light-receiving surface 12a of the second light-absorbing body 12 receive. The second light-absorbing body 12 absorbs a large part of the reflected light and reflects a part thereof toward the first light-absorbing body 11 , Through the second light-absorbing body 12 reflected light is from a tertiary light-receiving surface 11b of the first light-absorbing body 11 receive. The reflected light partially becomes in the first light-absorbing body 11 absorbed and the remaining part in turn becomes the second light-absorbing body 12 reflected.

As 2 2, in the second embodiment partially overlaps the primary light receiving surface 11a which receives incident light and the tertiary light-receiving surface 11b which through the second light-absorbing body 12 receives reflected light. In other words, in the second embodiment, the first light-absorbing body 11 and the second light-absorbing body 12 arranged so that incident light and through the second light-absorbing body 12 reflected light at least partially on the first light-absorbing body 11 overlap. Therefore, the angle Θ, the first light-absorbing body 11 and the second light-absorbing body 12 can be set relatively large, thus producing a small, light-weight optical absorber 10 is possible at low cost.

According to 2 is a first cooling unit 15 on the surface of the first light-absorbing body 11 which is opposite to the light receiving surface, and a second cooling unit 16 is on the surface of the second light-absorbing body 12 disposed opposite to the light receiving surface. The first cooling unit 15 and the second cooling unit 16 act as a cooling Plates or cooling fins through which, for example, a coolant flows, in particular in the interior.

The first light-absorbing body 11 and the second light-absorbing body 12 absorb laser light and generate heat, being the first cooling unit 15 and the second cooling unit 16 suppress the heating. This makes it possible to prevent damage to the first light-absorbing body 11 and on the second light-absorbing body 12 due to heat generation and thus the lifetime and the functional reliability of the optical absorber 10 be improved. Instead of using the first cooling unit 15 and the second cooling unit 16 may also have a passage (channel) within the first light-absorbing body 11 and the second light-absorbing body 12 be formed so that a coolant through the passage (channel) can flow.

2 also shows a connection component 18 , which is the first light-absorbing body 11 and the second light-absorbing body 12 connects with each other. The connection component 18 is on the side surfaces of the first light-absorbing body 11 and the second light-absorbing body 12 attached to heat between the first light-absorbing body 11 and the second light-absorbing body 12 transferred to. With such a connection component 18 can be one of the two mentioned cooling units 15 respectively. 16 be omitted. This keeps the manufacturing cost of the optical absorber 10 low.

4 Fig. 7 is a graph showing the relationship between the attenuation ratio and the number of reflections. 4 shows the attenuation ratio on the ordinate and the number of reflection on the abscissa. 4 also shows a required attenuation ratio B for the optical absorber 10 ,

The curve A1 according to 4 is obtained with a reflectivity of both the first light-absorbing body 11 as well as the second light-absorbing body 12 of 10%. The curve A2 according to 4 is obtained when the reflectivity of the first light-absorbing body 11 to 50% and the reflectance of the second light-absorbing body 12 set to 10%. The curve A3 according to 4 is obtained when the reflectivity of both the first light-absorbing body 11 as well as the second light-absorbing body 12 set to 50%.

How out 4 can be seen, according to curve A1 the attenuation ratio is set smaller than the required attenuation ratio by a relatively small number of reflections B , In this case, however, the light resistance is low, as is apparent 3 results. Therefore, as mentioned above, the angle Θ must be set small, resulting in a large optical absorber 10 results. In the case of the curve A3 becomes the total length L of the optical absorber 10 preferably set long because of a large number of reflections, although the light resistance is high.

On the other hand, in the case of the curve A2, the attenuation ratio can be set smaller than the required attenuation ratio B without increasing the number of reflections. Accordingly, the reflectance of the first light-absorbing body is 11 preferably about 50%, such as between 40% and 60%, and the reflectivity of the second light-absorbing body 12 is preferably about 10%, such as a value greater than 0% and less than 20%. It turns out that with these values a functionally reliable optical absorber 10 can be provided with little effort.

ADVANTAGEOUS EFFECTS OF THE INVENTION

In the first invention, since incident light enters a first light-absorbing body having high reflectivity and high light resistance, high-intensity incident light can not damage the first light-absorbing body. Reflected light is guided and absorbed in a second light-absorbing body having low reflectivity and small light resistance. Since the reflected light is attenuated by the first light-absorbing body, the second light-absorbing body is not damaged either. In this way, the use of only the first light-absorbing body and the second light-absorbing body having different reflectivities and light resistances enables the production of a functionally reliable optical absorber at a low cost.

In the second invention, since areas other than the entrance opening are closed, safety can be improved. Since the number of reflections in the optical absorber can be increased, the laser light is reliably absorbed there.

In the third invention, the angle which the first light-absorbing body and the second light-absorbing body include can be set relatively large, so that a small optical absorber can be manufactured with a low weight and a low cost.

In the fourth invention, since the temperature of the light-absorbing body can be kept low by a cooling unit, the life of the optical absorber can be prolonged to improve the safety and reliability of the optical absorber.

In the fifth invention, when only one of said first and second light-absorbing bodies is provided with a cooling unit, a connecting member enables heat transfer. Therefore, only one cooling unit is sufficient, which also reduces the manufacturing costs.

According to the sixth and seventh inventions, a functionally reliable optical absorber can be provided with a relatively simple structure at a low cost.

Claims (7)

Optical absorber (10), comprising: a first light absorbing body (11) adapted to receive incident light via an input port (10a) and to partially absorb and partially reflect the incident light; and a second light-absorbing body (12) adapted to partially absorb the incident light reflected by the first light-absorbing body (11) and partially to reflect the incident light to the first light-absorbing body (12), the first light-absorbing body and the first light-absorbing body second light-absorbing bodies form rectangular parallelepipeds defined by planes; wherein the end portions of the first light-absorbing body and the second light-absorbing body are connected to each other downstream of the direction in which the laser light propagates; and wherein a light absorption of the second light-absorbing body (12) is set higher than a light absorption of the first light-absorbing body (11). Optical absorber according to Claim 1 wherein a space enclosed by the first light-absorbing body and the second light-absorbing body is closed except for the entrance opening. Optical absorber according to one of Claims 1 or 2 wherein the incident light and the light reflected by the second light-absorbing body overlap at least partially in the first light-absorbing body. Optical absorber according to one of Claims 1 to 3 , further comprising a cooling unit (15, 16) arranged to cool the first light-absorbing body and / or the second light-absorbing body. Optical absorber according to Claim 4 , further comprising a connecting member (18) arranged to connect the first light absorbing body and the second light absorbing body for heat transfer. Optical absorber according to one of Claims 1 to 5 wherein the first light-absorbing body has a reflectivity between 40 and 60%. Optical absorber according to one of Claims 1 to 6 wherein the second light-absorbing body has a reflectance greater than 0% and less than or equal to 10%.

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